It is well known to use a variety of different electro-optical sensors in advanced electro-optical payloads. Examples of this include the use of a television camera and optical system together with a image intensification or infrared sensor, the use of one of these sensors together with a laser and the combination of these sensor systems and a laser.
In an optical system such as mentioned above, boresighting is necessary to ensure that the laser is aimed at a target intercepting the line of sight of the sensor.
Although boresighting is generally carried out prior to operation of the optical systems, such that the system is not yet engaged in `viewing` the target, it is also known to carry out boresighting while the system is in use. If the system includes, for example, a tracking system which is operative to lock onto the target, boresighting conventionally interrupts the tracking operation and the target is `lost`. The total time lost is the time it takes to achieve boresighting plus the time it takes to lock onto the target once again.
Boresighting is conventionally carried out by using an elongated corner-cube assembly in conjunction with a laser and a sensor, both of which form part of a combined system. The corner-cube is mounted for rotation about an axis generally parallel to the lines of sight of the laser and the sensor and comprises a roof mirror at one end and a plane mirror at the other end. In a non-boresighting situation, the corner-cube is oriented such that the lines of sight of the laser and the sensor are unobstructed.
When, however, boresighting is to be performed, the corner-cube is rotated about the axis such that the roof mirror and the plane mirror obstruct the lines of sight of the laser and the sensor so as to interrupt use of the combined system until after boresighting has been completed.